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                改编                </h1>
                <p>时间限制：10s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><div style="text-indent: 24pt"><span style="font-size: 12pt">A:</span><span style="font-size: 12pt">&ldquo;大图书馆是一张n点m边的无向图，Marisa和Patchouli初始分别位于点X和点Y。每分钟，两人都有一次行动机会：当某人位于点i时，有pi的概率停留在点i，有1-pi的概率等概率随机选择点i的相邻节点之一并前往。若两人在某个点相遇，则行动停止。值得注意的是，两人在边上是不会相遇的，所以两人在某条边上迎面经过，只会错过而不会相遇。两人同时行动，求两人在每个点相遇的概率。&rdquo;</span></div>
<div style="text-indent: 24pt"><span style="font-size: 12pt">B</span><span style="font-size: 12pt">：&ldquo;这不是CodeForces 113 D吗，还原度真高啊喂。&rdquo;</span></div>
<div style="text-indent: 24pt"><span style="font-size: 12pt">A</span><span style="font-size: 12pt">：&ldquo;那改一改&hellip;&hellip;不求在每个点相遇的概率，改成求两人在相遇前走过的路径长度期望和。&rdquo;</span></div>
<div style="text-indent: 24pt"><span style="font-size: 12pt">B</span><span style="font-size: 12pt">：&ldquo;大同小异。&rdquo;</span></div>
<div style="text-indent: 24pt"><span style="font-size: 12pt">A</span><span style="font-size: 12pt">：&ldquo;大图书馆的m条边的长度是可以修改的，两人的初始位置也是。&rdquo;</span></div>
<div style="text-indent: 24pt"><span style="font-size: 12pt">B</span><span style="font-size: 12pt">：&ldquo;你不要让Patchouli太累了&hellip;&hellip;&rdquo;</span></div>
<div style="text-indent: 24pt">&nbsp;</div></p><hr/><h3>输入格式</h3><p><div style="text-indent: 21pt"><span style="font-size: 12pt">第一行三个正整数n、m、t，表示点数、边数和数据组数</span></div>
<div style="text-indent: 21pt"><span style="font-size: 12pt">以下m行，每行2个整数a,b，表示点a和点b之间有一条无向边</span></div>
<div style="text-indent: 21pt"><span style="font-size: 12pt">接下来一行n个实数表示pi，保证0.01&lt;=pi&lt;=0.99</span></div>
<div style="text-indent: 21pt"><span style="font-size: 12pt">以下t行，每行前m个整数表示每条边的长度，最后2个整数表示初始位置点X和点Y</span></div></p><hr/><h3>输出格式</h3><p><div>&nbsp;</div>
<div style="text-indent: 21pt"><span style="font-size: 12pt">共t行，每行一个实数表示两人在相遇前走过的路径长度期望和（保留2位小数）</span></div></p><hr/><h3>样例输入</h3><pre>4 4 2
1 2
2 3
3 4
1 4
0.5 0.5 0.5 0.5
1 1 1 1 1 2
2 2 2 2 1 3
</pre><hr/><h3>样例输出</h3><pre>4.67
10.67
</pre><hr/><h3>提示</h3><p><p>对于100%的数据，1&lt;=n&lt;=22,t&lt;=500，1&lt;=边权&lt;=1000000<br />
保证图是无重边和自环的连通图</p></p><hr/><h3>题目来源</h3><p>高斯消元法</p>
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